T6 - CNS Virus

What is the definition of neurotropism?

Selective affinity for nervous tissue

Which viral entry route is typically utilized by the rabies virus?

Peripheral nerves

Which CNS viral entry route involves crossing the BBB or Blood-CSF barrier?

Blood-borne invasion

Which viral family is the most frequent cause of CNS infections globally?

Enterovirus (EV)

What is the primary transmission route of Enterovirus (EV)?

Fecal-oral route

What is the most common CNS clinical manifestation of Enterovirus?

Meningitis

What are the primary CNS manifestations of Herpes Simplex Virus (HSV)?

Meningitis and Encephalitis

What is the primary transmission source for the rabies virus?

Contact with infected mammals

What is the primary CNS manifestation of Varicella-zoster virus (VZV)?

Encephalitis

Which viral entry method to the CNS involves tight junctions?

Transcellular/paracellular spread

To which viral family and genus does the poliovirus belong?

Picornaviridae, Enterovirus

What type of genome does the poliovirus possess?

Linear (+)ssRNA

Is the poliovirus enveloped or non-enveloped?

Non-enveloped

What is the only known host for the poliovirus?

Human

Why is the poliovirus able to survive in the human GI tract?

It is acid-stable

What is the primary transmission route of the poliovirus?

Fecal-oral route

Which viral proteins make up the capsid of the poliovirus?

VP1, VP2, VP3, VP4

Which region of the poliovirus genome encodes the capsid proteins?

P1 region

Which regions of the poliovirus genome encode the nonstructural proteins?

P2 and P3 regions

What is the function of the 5' NCR in the poliovirus genome?

Internal ribosome entry site (IRES)

Which poliovirus protein is primarily responsible for binding to the host CD155 receptor?

VP1

What is the function of the poliovirus VPg protein?

Primer for RNA synthesis

Which poliovirus protease cleaves host cell eIF4G to shut down host protein synthesis?

2A (Pro)

Which poliovirus accessory protein inhibits ER-to-Golgi protein trafficking?

3A

Which poliovirus protein serves as the RNA-dependent RNA Polymerase (RdRp)?

3D (pol)

Which cellular receptor does the poliovirus bind to?

CD155 (PVR)

By which mechanism does poliovirus enter the host cell?

Non-clathrin-mediated endocytosis

Where does poliovirus initially replicate after fecal-oral entry?

Peyer's patches and lymphoid tissues

Which specific neural cells are the major target of poliovirus neurotropism?

Anterior Horn Cells

Which viremic stage facilitates poliovirus spread to the spinal cord?

Major/secondary viremia

What physiological mechanism causes Post-Polio Syndrome?

Degeneration of new axonal sprouts

What is the most common clinical presentation of a poliovirus infection?

Asymptomatic

Which cranial nerves are affected in Bulbar Polio?

Cranial nerves IX, X, XII

What is the gold standard method for diagnosing poliovirus?

Viral isolation from stool or CSF

What type of vaccine is the Inactivated Poliovirus Vaccine (IPV/Salk)?

Killed/Inactivated vaccine

Which primary immunoglobulin is triggered by the Oral Poliovirus Vaccine (OPV/Sabin)?

Secretory IgA

What is the primary risk associated with the Oral Poliovirus Vaccine (OPV)?

Vaccine-associated paralytic polio (VAPP)

To which viral family and genus does the rabies virus belong?

Rhabdoviridae, Lyssavirus

What type of genome does the rabies virus possess?

Linear (-)ssRNA

What is the characteristic shape of the rabies virion?

Bullet-shaped

What are the characteristic pathognomonic inclusions formed by rabies in neurons?

Negri bodies

Which rabies protein mediates attachment to the nicotinic acetylcholine receptor?

Spike glycoprotein (G)

What is the typical incubation period for the rabies virus?

Weeks to months

Which medical procedure represents a rare human-to-human transmission route for rabies?

Solid organ transplantation

Which rabies strain is characterized by high neuroinvasiveness and localized brain distribution?

Street Strain (Wild-type)

Which rabies strain is characterized by low neuroinvasiveness and diffuse brain distribution?

Vaccine/Fixed Strain

Which rabies structural protein binds to viral RNA to form the nucleocapsid?

Nucleoprotein (N)

Which rabies protein functions as the RNA-dependent RNA polymerase?

Large protein (L)

By which mechanism are rabies virions released from the host cell?

Budding

A 35-year-old animal control officer is bitten by a dog. Where does the rabies virus initially replicate?

Muscle tissue

A 12-year-old child is scratched by a bat. Which cellular receptor facilitates the entry of the rabies virus into the peripheral nerves?

Nicotinic acetylcholine receptors (nAChR)

A 40-year-old man develops rabies encephalitis. By which transport mechanism did the virus reach the CNS from the peripheral inoculation site?

Retrograde axonal transport

A patient with late-stage rabies exhibits high viral titers in the saliva. Which mechanism spreads the virus from the brain to the salivary glands?

Centrifugal spread

A 28-year-old male presents with agitation, hyperexcitability, and aerophobia. Which clinical stage of rabies does this represent?

Encephalitic (Furious) Rabies

A 50-year-old farmer develops ascending paralysis two months after a fox bite. Which clinical form of rabies is this?

Paralytic (Dumb) Rabies

A 20-year-old patient develops symptoms of rabies encephalitis. What is the expected timeline for a fatal outcome?

7-10 days

A 45-year-old man dies of undiagnosed encephalitis. Post-mortem histopathology reveals Negri bodies. What is the diagnosis?

Rabies

A 30-year-old patient is suspected of having rabies. Which anatomical site is optimal for an antemortem direct fluorescent antibody test (DFAT)?

Skin biopsy (neck region)

A pathologist examines a brain slice from a suspected rabies victim. What is the characteristic staining pattern of Negri bodies?

Eosinophilic

In a post-mortem examination of a rabies victim, which specific cells are most notable for containing Negri bodies?

Purkinje cells

A laboratory uses a molecular assay for rapid diagnosis of rabies. Which specific RT-PCR assay is recommended?

LN34 real-time RT-PCR assay

A veterinary worker is checked for rabies immunity. Which serology test evaluates virus neutralization?

RFFIT

A 10-year-old boy suffers a Category III bite from a wild raccoon. What are the required components of his post-exposure prophylaxis?

Rabies Immune Globulin (RIG) + Rabies Vaccine

A patient requires Human Rabies Immune Globulin (HRIG) after a severe dog bite. How is HRIG prepared?

From the plasma of hyperimmunized human donors

A clinic in a developing region administers Equine Rabies Immune Globulin (ERIG). What is the primary disadvantage compared to HRIG?

Higher risk of adverse reactions

A child strokes a healthy-looking dog on intact skin (Category I contact). What is the recommended treatment plan?

No treatment

A man is bitten by his fully vaccinated, well-cared-for pet dog. During the 10-day observation, the dog remains healthy. What is the protocol?

No treatment or post-exposure prophylaxis